Recent studies demonstrate that, in addition to controlling distal-limb musculature, the cerebellar hemispheres and dentate nuclei also influence eye movements and probably hand eye coordination. Anatomical studies have shown that the dentate nuclei receive inputs from visual and vestibular pathways and that dentate neurons, in turn have a surprisingly large number number of connections with major oculomotor centers of the midbrain and In the present proposal we have established two goals concerning the the cerebellar control of eye movements. The first goal is to examine the movement related activity of dentate neurons in the alert cat preparation preparation and to study the anatomical organization and processing of andvestibular information within this nucleus. The second goal is a more a more general question regarding the specificity of visual-vestibular convergence. These experiments in alert cats and rats will examine the three dimensional optokinetic and vestibular receptive field characteristics of individual dentate neurons involved with the vertical vestibulo-ocular reflex (VOR) and Purkinje cells of the cerebellar flocculus which control components of the horizontal and vertical VOR. Standard electrophysiological recording techniques will be used to study single antidromically identified cerebellar neurons, to examine their responses to optokinetic and vestibular stimulation, and in the case of dentate neurons, to examine the eye movement related activity during spontaneous saccades, gaze holding function slow and fast components of optokinetic and vestibular nystagmus. Anatomical tracers (Horseradish peroxidase, 3H-amino acids) will be employed to continue our analysis of the midbrain and brainstem structures conveying visual pursuit and optokinetic signals to the cerebellum. Among others (e.g., nucleus reticular is tegmenti pontis) an area we term the intrafascicular nucleus the medial longitudinal fascicularis is known from retrograde studies to project to the flocculus and receive descending visualinput but the full extent of their afferent connections and cerebellar efferent projections need to be determined. These studies will provide important information on neocerebellar control of eye movements as well as determining the importance of vision for the cerebellar control of horizontal and vertical compensatory eye movements and visually guided behavior.